1. Field of the Invention
The present invention relates to an image sensor pixel structure, and more particularly, to a backside illumination (hereinafter abbreviated as BSI) image sensor pixel structure.
2. Description of the Prior Art
With the development of computer and communications industries, demand for high-efficiency image sensor has been increased. Such image sensors are used in various fields, such as digital cameras, camcorders, personal communications systems, game components, monitors, medical micro camera, robots, etc.
BSI image sensors are popular high-efficiency image sensors in the present industry. Because BSI image sensor fabrication can be easily integrated into conventional semiconductor processes, it has advantages of low cost, tiny size, and high integration. Moreover, BSI image sensor itself further has advantages of low operation voltage, lower power consumption, high quantum efficiency, low read-out noise, and random access. Therefore, BSI image sensor is prevalently adopted in the aforementioned electronic products.
With the progress in the semiconductor manufacturing technology, BSI image sensor confronts further demands not only for ever-decreasing size, but also for improvement on photo-electric conversion efficiency and sensitivity, and low noise. Briefly speaking, improvement is always in need.